Acute exercise and GLUT4 expression in human skeletal muscle: influence of exercise intensity.

To examine the influence of exercise intensity on the increases in vastus lateralis GLUT4 mRNA and protein after exercise, six untrained men exercised for 60 min at 39 +/- 3% peak oxygen consumption (V(O2 peak)) (Lo) or 27 +/- 2 min at 83 +/- 2% V(O2 peak) (Hi) in counterbalanced order. Preexercise muscle glycogen levels were not different between trials (Lo: 408 +/- 35 mmol/kg dry mass; Hi: 420 +/- 43 mmol/kg dry mass); however, postexercise levels were lower (P < 0.05) in Hi (169 +/- 18 mmol/kg dry mass) compared with Lo (262 +/- 35 mmol/kg dry mass). Thus calculated muscle glycogen utilization was greater (P < 0.05) in Hi (251 +/- 24 mmol/kg) than in Lo (146 +/- 34). Exercise resulted in similar increases in GLUT4 gene expression in both trials. GLUT4 mRNA was increased immediately at the end of exercise (approximately 2-fold; P < 0.05) and remained elevated after 3 h of postexercise recovery. When measured 3 h after exercise, total crude membrane GLUT4 protein levels were 106% higher in Lo (3.3 +/- 0.7 vs. 1.6 +/- 0.3 arbitrary units) and 61% higher in Hi (2.9 +/- 0.5 vs. 1.8 +/- 0.5 arbitrary units) relative to preexercise levels. A main effect for exercise was observed, with no significant differences between trials. In conclusion, exercise at approximately 40 and approximately 80% V(O2 peak), with total work equal, increased GLUT4 mRNA and GLUT4 protein in human skeletal muscle to a similar extent, despite differences in exercise intensity and duration.     

Ruthenium red staining reveals surface fibrils and a layer external to the cell wall in Streptococcus salivarius HB and adhesion deficient mutants

Ruthenium red staining revealed both the long and short classes of cell surface fibril in thin sections of Streptococcus salivarius HB, indicating that the fibrils contained polyanionic polymers, probably polysaccharides. Also visible was a 16.2 +/- 2.2 nm thick ruthenium red staining layer (RRL) outside the 16.7 +/- 2.2 nm thick cell wall. The fibrils could not be seen after conventional glutaraldehyde and osmium fixation. The RRL was protease resistant and was not involved in septum formation. Loss of the fibrils after protease treatment coincided with a decrease of 54% in cell surface hydrophobicity, indicating that cell surface hydrophobicity was due partly to fibrils and partly to the RRL. There was no correlation between the lengths of fibrils as measured on whole cells after negative staining and on thin sections of ruthenium red stained cells. The thickness of the RRL was the same in three adhesion deficient mutants--strains HB-7, HB-V5 and HB-V51--with various fibril lengths. However, a completely bald mutant, HB-B, had a significantly thicker RRL than S. salivarius HB, although it was unable to adhere to buccal epithelial cells, and it could not co-aggregate with Veillonella parvula V1. The RRL therefore did not contain adhesins.     

Biology and energetics of the gall inducing aphids Aphis pomi and Dysaphis devecta

Larval growth, reproduction and energetics of Aphis pomi was determined for apterae living and feeding in the newly formed and 2 or 3 week old pseudogalls. Aphids were reared on stems and mature leaves. Similar investigations were undertaken with apterous Dysaphis devecta in its own gall and with the alatiform living in the aptera gall or on young leaves.The beneficial effect of feeding in galls is soon lost because aptera growth rate is 0.015 dry mg day^–1 in young galls but falls to 0.0045 dry mg day^–1 in older galls, a decline of 30%. Larval life is correspondingly extended by 50%. Mean life time fecundity of A. pomi in young galls was 55 but in older galls or on nongalled tissue it was 23. Fecundity of D. devecta apterae was 71 compared to 34 for alatiforms living in similar galls.Life time energy consumption of A. pomi in young galls was 62.5 joules (J) with a mean of 31.2 joules in older galls. The assimilation/consumed energy (A/C) ratio, an indicator of food quality, was 57% for A. pomi in young galls and 22% on other feeding sites. Apterous D. devecta had an A/C ratio of 76% compared to a mean of 31% for alatiforms within and outside galls.The highly specialized gall inhabiting D. devecta apterae derive greater physiological benefit from gall feeding than the generalis A. pomi which can survive and reproduce within or outside its gall.

---

Résumé Le développement larvaire, la reproduction et le bilan énergétique d'A. pomi ont été déterminés à partir d'aptères vivant et s'alimentant dans des galles venant d'être formées et de pseudogalles de 2 à 3 semaines. Les pucerons ont été élevés sur des pousses et des feuilles développées. Des recherches du même type ont été faites sur Dysaphis devecta aptères dans ses propres galles et sur des alatiformes vivant dans des galles d'aptères ou sur de jeunes feuilles.Les effects bénéfiques de l'alimentation dans des galles a été rapidement perdu puisque les aptères ont crû à la raison de 0,015 mg de matière sèche par jour dans des jeunes galles et de 0,0045 seulement dans les galles plus âgées, soit une diminution de 40%. La durée du développement larvaire s'étant parallèlement accrue de 50%. La fécondité moyenne de A. pomi était de 55 dans les jeunes galles contre 23 dans les galles plus âgées sur des tissus ordinaires. La fécondité de D. devecta aptère était de 71 contre 34 pour les alatiformes vivant sur les mêmes tissus.Le bilan énergétique global de A. pomi dans de jeunes galles était de 62,5 j contre 31,2 j dans des galles plus âgées. Le rapport d'assimilation sur énergie consommée (A/C), — indicateur de qualité de l'alimentation —, était de 0,57 pour A. pomi dans des galles jeunes et de 0,22 dans les autres situations. D. devecta aptère avait 0.76 comme rapport A/C contre 0,31 pour les alatiformes se développant à l'intérieur ou à l'extérieur des galles. D. devecta aptère fortement spécialisé au développement dans des galles tire un plus grand bénéfice physiologique de la consommation dans des galles que A. pomi généraliste qui peut survivre et se reproduire tant à l'intérieur qu'à l'extérieur de galles.

     

Reconstitution of intermediate filaments from a higher plant.

Immunological studies have shown that plants contain intermediate-filament antigens, but it is not known whether these proteins are capable in themselves of forming filaments. To address this problem, a detergent-resistant and high-salt-insoluble fraction from carrot (Daucus carota L.) suspension cells was solubilized with 9 M-urea and then subjected to a two-step dialysis procedure, devised for the reconstitution of animal intermediate filaments. This induced the self-assembly of 10 nm filaments and large bundles of filaments. The predominant components of reconstituted material were polypeptides with apparent molecular masses between 58 and 62 kDa. These polypeptides immunoblotted with two monoclonal antibodies known to show broad cross-reactivity with intermediate filaments across the phylogenetic spectrum. This establishes that the antigens are able to self-assemble into intermediate-sized filaments.     

Chromatin changes in apoptosis

Summary Murine lymphoid cell lines and rat thymocytes treatedin vitro with glucocorticoid hormones provide a convenient system for studying the nuclear changes in apoptosis. Morphologically the nucleolus disintegrates and chromatin undergoes an unusual, generalized condensation. This is associated with excision of most of the nuclear. DNA to short but well-organized chains of nucleosomes, apparently by an endogenous non-lysosomal nuclease. The process is dependent upon macromolecular synthesis and probably is mediated, at least remotely, by the classical steroid-receptor-gene activation pathway. A similar process of chromatin condensation and excision can be produced by the calcium-magnesium ionophore A23187. In other circumstances of programmed cell death', analogous chromatin condensation, excision and requirements for macromolecular synthesis have been documented.     

Engaging New Migrants in Infectious Disease Screening: A Qualitative Semi-Structured Interview Study of UK Migrant Community Health-Care Leads

Migration to Europe - and in particular the UK - has risen dramatically in the past decades, with implications for public health services. Migrants have increased vulnerability to infectious diseases (70% of TB cases and 60% HIV cases are in migrants) and face multiple barriers to healthcare. There is currently considerable debate as to the optimum approach to infectious disease screening in this often hard-to-reach group, and an urgent need for innovative approaches. Little research has focused on the specific experience of new migrants, nor sought their views on ways forward. We undertook a qualitative semi-structured interview study of migrant community health-care leads representing dominant new migrant groups in London, UK, to explore their views around barriers to screening, acceptability of screening, and innovative approaches to screening for four key diseases (HIV, TB, hepatitis B, and hepatitis C). Participants unanimously agreed that current screening models are not perceived to be widely accessible to new migrant communities. Dominant barriers that discourage uptake of screening include disease-related stigma present in their own communities and services being perceived as non-migrant friendly. New migrants are likely to be disproportionately affected by these barriers, with implications for health status. Screening is certainly acceptable to new migrants, however, services need to be developed to become more community-based, proactive, and to work more closely with community organisations; findings that mirror the views of migrants and health-care providers in Europe and internationally. Awareness raising about the benefits of screening within new migrant communities is critical. One innovative approach proposed by participants is a community-based package of health screening combining all key diseases into one general health check-up, to lessen the associated stigma. Further research is needed to develop evidence-based community-focused screening models - drawing on models of best practice from other countries receiving high numbers of migrants.     

Selective depletion of activated T cells: the CD40L-specific antibody experience

Blocking the signal that provides co-stimulation to T cells during their encounter with antigen is thought to make T cells anergic or tolerant. Recently, treatments using CD40L-specific antibody, a co-stimulation blocking reagent, in primate transplant models indicated that this elegant concept could finally be turning into reality. In this context, the finding that CD40L-specific antibody acts through depletion of activated T cells rather than through co-stimulation blockade might seem undesirable. However, the selective removal of cells that are key effectors of immunopathology could provide a powerful tool for containing unwanted immune responses such as those that mediate autoimmune diseases and transplant rejection.